The field of this invention relates to a carburetor and more particularly to a carburetor with a separate nozzle post member.
Many carburetors have a fuel float movably mounted in a lower fuel chamber that is attached to a one-piece carburetor body for opening and closing a fuel supply valve for supplying fuel to the fuel chamber. The carburetor body generally is cast with an integrally formed upper body section with an intake passage therethrough and a tower which has an intake nozzle which extends into the lower fuel chamber. The one piece design of the tower and main body section results in a relatively thick cast section which may promote undesirable porosity. An idle fuel path, intake air passage and vent passage also passes through the tower. The fuel and air routing through the nozzle and carburetor is typically accomplished by multiple drilled holes in the casting. Many of these passages are narrow and deep such that they require multiple successive drilling operations to reach full depth. Many of these drillings are to form internal interconnections for which the exterior portion of the drilling must then be subsequently plugged. In addition, some of these drillings are not parallel or perpendicular to the throttle bore axis, i.e. they are angled which provides for a more difficult machining operation.
While many of the casting, drilling and plugging operations are automated, the high number of operations to one carburetor body adds time and thus expense to the manufacture of such carburetors. Furthermore the large casting requires an appropriately long die cast cycle time. The use of plugs also creates a risk that one may be omitted or they may create an undesirable leak path.
What is needed is an expeditiously manufactured carburetor that reduces the cost of manufacture and increases reliability.
In accordance with one aspect of the invention, a carburetor has an upper carburetor body and a lower fuel chamber carried by the body. An intake passage through the body has an air inlet and a fuel and air mixture outlet. The carburetor includes a separate nozzle post member having a flange seated onto a lower face of the upper carburetor body and a depending post that extends into the fuel chamber. The depending post has a vertical bore therethrough and a main fuel jet inlet at its lower end. A main fuel nozzle extends into the vertical bore in the depending post. The main fuel nozzle has an axially extending mixing passage therethrough with an axial end inlet for receiving fuel from the main jet inlet, at least one side aperture for allowing air to pass therein to mix with the fuel, and an outlet forming the main fuel nozzle in communication with the intake passage through the upper carburetor body.
An air passage within the depending post is adjacent the nozzle and is in communication with the side apertures and in communication with an air path through the upper carburetor body for receiving air therefrom. Preferably, the outlet of the nozzle extends laterally into the intake passage. It is also desirable that the air passage is annular in shape and circumferentially surrounds the nozzle.
The main jet fuel inlet is in communication with an idle fuel passage extending axially in the depending post and an idle fuel path in the upper carburetor body. Preferably, the idle fuel passage is annular in shape and circumferentially surrounds the annular air passage.
In accordance with one embodiment, the main fuel jet inlet is formed in an intermediate member with the nozzle extending into the intermediate member. The annular air passage is formed between the nozzle and the intermediate member. The annular idle fuel passage is formed between the intermediate member and the depending post.
It is preferable that the depending post has an integrally formed siphon passage extending downwardly with its lower opening in proximity to a floor surface of said fuel chamber.
In accordance with another aspect of the invention, the seperate nozzle post member is seated onto a lower face of the upper carburetor body and extends into the lower fuel chamber. The seperate nozzle post member has a integrally formed bracket for pivotably mounting a float valve. The float valve has a fuel valve preferably housed in the seperate nozzle post member for opening and closing a fuel supply port formed in the seperate nozzle post member.